Cerebral structures participating in motor preparation in humans: A positron emission tomography study
Cerebral structures participating in motor preparation in humans: A positron emission tomography study
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DOI：
10.1152/jn.1996.75.1.233
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发表时间：
1996-01-01
影响因子：
2.5
通讯作者：
Hallett, M
中科院分区：
文献类型：
--
作者：
Deiber, MP;Ibanez, V;Hallett, M
1.采用正电子发射断层扫描和测量局部脑血流量(rCBF)作为脑活动指标，我们研究了13名健康志愿者运动准备的中枢处理过程。2．我们使用运动反应时间范例，以视觉提示作为准备和响应信号。预备刺激 (PS) 提供有关即将到来的右手手指运动的两个变量的全部、部分或不提供信息：手指类型（食指或小指）和运动方向（外展或抬高）。经过一段可变的延迟期后，反应刺激 (RS) 促使运动。还测试了受试者在准备期间可以自由选择四种可能运动中的任何一种的条件（“自由”条件）。事件计时的目的是在 1 分钟的扫描时间内强调运动准备阶段而不是运动执行部分。3。不同的准备过程取决于 PS 中包含的信息，并通过条件之间反应时间的显着差异得到证明。在“完全”和自由条件下反应时间较短，在两种部分信息条件（“手指”和“方向”）下反应时间居中，而在没有准备信息可用时（“无”条件）反应时间较长。相反，不同条件下的运动时间和运动幅度相似，建立了运动执行输出的稳定性。4．与视觉输入相匹配的“休息”条件相比，不同的运动准备条件与一组常见大脑区域的rCBF增加相关：对侧额叶皮层（感觉运动皮层、前运动皮层、扣带回皮层和辅助运动皮层）、对侧顶叶联合皮层（前部和后部区域）、同侧小脑、对侧基底神经节和丘脑。这一观察证实了这些大脑结构参与运动准备。此外，与休息条件相比，不同条件下激活区域的相似性表明用于运动准备的单一解剖基质，独立于运动信息上下文。5。 PS 中包含的不同数量的运动信息影响了某些大脑区域的 rCBF 变化。特别是，与无条件相比，前顶叶皮层（布罗德曼区 40）的 rCBF 在完全、手指和方向条件下分别显着更大。这一观察结果支持了这样的假设：前顶叶联合皮层在使用 PS 中包含的视觉指令来部分或完全准备执行运动动作方面发挥着重要作用。另一方面，后顶叶联合皮层（布罗德曼区 7）在手指、方向和无状态下比在完整状态下更活跃。这种在有限的预先信息下活动的增加表明，顶叶皮层的后部区域与基于对 RS.6 增强的空间注意力的正确运动选择有关。与顶叶皮层相比，次级运动区域（即运动前皮层、扣带皮层和辅助运动区域）表现出相似的活动，无论预先视觉信息允许的准备程度如何。因此，在整合视觉信息以准备运动方面，顶叶皮层可能比次级运动区发挥更重要的作用。7．通过比较自由条件和完全条件，评估内部（自生）与外部（提示）运动选择模式对大脑活动的影响，准备部分在两种条件下相匹配。辅助运动区的前部是优先参与运动内部选择的主要区域，与运动准备过程无关。
1. Using positron emission tomography and measurement of regional cerebral blood flow (rCBF) as an index of cerebral activity, we investigated the central processing of motor preparation in 13 healthy volunteers.2. We used a motor reaction time paradigm with visual cues as preparatory and response signals. A preparatory stimulus (PS) provided either full, partial, or no information regarding two variables of a forthcoming right finger movement: finger type (index or little finger) and movement direction (abduction or elevation). After a variable delay period, a response stimulus (RS) prompted the movement. A condition was also tested in which the subject could freely select any of the four possible movements during the preparation period (''free'' condition). The timing of events was designed to emphasize the motor preparation phase over the motor execution component during the scanning time of 1 min.3. Distinct preparatory processes, which depended on the information contained in the PS, were demonstrated by significant differences in reaction time between conditions. The reaction time was shorter in the ''full'' and free conditions, intermediate in the two partial information conditions (''finger'' and ''direction''), and longer when no preparatory information was available (''none'' condition). Conversely, movement time and movement amplitude were similar between conditions, establishing the constancy of the motor executive output.4. In comparison with a ''rest'' condition, which had matched visual inputs, the different conditions of motor preparation were associated with increased rCBF in a common set of cerebral regions: the contralateral frontal cortex (sensorimotor, premotor, cingulate, and supplementary motor cortex), the contralateral parietal association cortex (anterior and posterior regions), the ipsilateral cerebellum, the contralateral basal ganglia, and the thalamus. This observation substantiates the participation of those cerebral structures in the preparation for movement. Furthermore, the similarity of the activated areas among the different conditions compared with the rest condition suggests a single anatomic substrate for motor preparation, independent of the movement information context.5. Differing amounts of movement information contained in the PS affected rCBF changes in some cerebral regions. In particular, the rCBF in the anterior parietal cortex (Brodmann's area 40) was significantly larger in each of the full, finger, and direction conditions, individually, compared with the none condition. This observation supports the hypothesis that the anterior parietal association cortex plays a major role in the use of visual instructions contained in the PS for partial or complete preparation to perform a motor act. On the other hand, the posterior parietal association cortex (Brodmann's area 7) was more activated in the finger, direction, and none conditions than in the full condition. This increased activity with restricted advance information suggests that the posterior region of the parietal cortex is concerned with correct movement selection on the basis of enhanced spatial attention to the RS.6. In contrast with the parietal cortex, the secondary motor areas (i.e, premotor cortex, cingulate cortex, and supplementary motor area) showed similar activity regardless of the degree of preparation allowed by the advance visual information. Thus the parietal cortex may play a more crucial role than the secondary motor areas in integrating visual information in preparation for movement.7. The effect on brain activity of the internal (self-generated) versus the external (cued) mode of movement selection was assessed by comparing the free and full conditions, the preparatory component being matched in the two conditions. The anterior part of the supplementary motor area was the main area preferentially involved in the internal selection of movement, independently of motor preparation processes.